/ Source: WVTM-TV
WASHINGTON -- New test results show aminopterin, a type of rat poison could be to blame for the massive pet food recall in the United States.
Food Lab's Dan Rice said he has "no idea how it could have gotten into the food product."
While the toxin is used to kill rats in other countries, it is only legal to use as a cancer-drug here in the U-S.
"There are any number of ways to contaminate food," said New York Agriculture Commissioner Patrick Hooker.
The Food and Drug Administration is focusing on wheat gluten in the pet food that's suspected of causing kidney failure in dogs and cats across the country...killing at least 16, including 15-month-old Abby.
"To see her deteriorate was very hard. In the end I literally carried her in to the vet," says Pam Sims, Abby's owner.
Those deaths led to the recall of 60-million cans and pouches of pet food made by Menu Foods under more than 95-brand names.
"It's hard, we do feel guilty because we trusted. You just trust it's going to be safe."
Even though pet owners and veterinarians may now know what caused the contamination, they still have to wait for answers about how it happened.
Wendy Woolfolk, NBC News.